CMAQ tracer namelist for CO2

Hi everyone, I am trying to use tracer namelist to add CO2 and CH4 in CMAQ runs. But I can’t understand the official tutorial, the tutorial made me very confused…
Would anyone provide me with a tracer namelist for CO2 or CH4.
I would really appreciate it.

Thank you in advance,

Example tracer namelist files are provided with the code according to this link.

The tracer namelist is generally interchangable between mechanisms. It can be employed for transport and deposition studies. Example tracer namelists are under $CMAQ_MODEL/CCTM/src/MECHS/trac0 (the version most often used) and $CMAQ_MODEL/CCTM/src/MECHS/trac1.